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Tip revision: d746e590f3aab108ea18c32f3ae3a4032da54c67 authored by ffxbld on 07 August 2015, 15:47:50 UTC
Added FIREFOX_40_0_RELEASE FIREFOX_40_0_BUILD5 tag(s) for changeset 84e0a4087157. DONTBUILD CLOSED TREE a=release
Tip revision: d746e59
Y.js
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// The Y combinator, applied to the factorial function

// Return the function that is the fixed point of f.
var Y = f => (x => f(v => x(x)(v)))
             (x => f(v => x(x)(v)));

// The factorial function is the fixed point of this:
var f = fac => n => (n <= 1) ? 1 : n * fac(n - 1);

print("5! is " + Y(f)(5));
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